: Hi, I have had a sewer smell in my house on several floors and several different places. I was told it : was methane (which we knew already). My question : is just how harmful is the methane gas and how worried should I be about it? I have small children too who might be affected. Thanks

The sewer smell itself is bad enough to endure for very long, but the gas is a different story.Methane is lighter than air and so rises to the higher spots in the house. It has varying danger potentials based upon its concentration, but is a dilute gas that doesn't flare very well.The rotten egg smell is hydrogen sulfide, not methane. Methane is relatively odorless. Hydrogen sulfide is very dangerous in heavy concentrations. Look at the description by typing hydrogen sulfide into your search engine. Hydrogen sulfide is even more dangerous to young persons who haven't yet developed full immune system capabilities. Be safe. Call a LICENSED plumber to stop the leakage. Protect your family.